[Coco] FDD 26pin to 34pin

[Gene Heskett]

On Tuesday 08 August 2006 09:51, Chester A Patterson wrote:
>OK. I figured as much. Most signals are no problem, DS0, DS1 and DS3
>(HS) have where to go... (please be patient, I'm learning and
>remembering, fast) I see now why we can only have up to 4 SS FDDs or 3
>DS FDDs. However, where to send the Coco DS2 signal on the 26pin FDD?
>And I guess the READY signal remains N/C?
>
This might be a  case of nobody ever used it (in a pc) so the 3rd drive 
feature went away.  In that event, twisted cable for the 3rd drive is 
required in order to steer DS2 to the DS1 pin on the third drive.

>Thanks.
>/Chester
>
>>>>>> <<<<<
>
>The floppy drives use a bus topology. All signals go to all drives.
>
>-Mike
>
>-----Original Message-----
>From: Mike Pepe [mailto:lamune at doki-doki.net]
>Sent: Monday, August 07, 2006 5:56 PM
>To: CoCoList for Color Computer Enthusiasts
>Subject: Re: [Coco] FDD 26pin to 34pin
>
>Chester A Patterson wrote:
>I think now I've got it gentlemen.
>Passing this info for your far more knowledgeable review and advice.
>
>Coco FDD interface (Disto)  PC FDD interface  FDD 26pin (Citizen OSDC)
>------------------------------------------------------------------------
>1	Gnd			    Gnd		    +5V
>2	N/C			    Density Select    INDEX
>3	Gnd			    Gnd		    +5V
>4	N/C			    N/C		    DRIVE SELECT 0
>5	Gnd			    Gnd		    +5V
>6	N/C			    N/C		    DRIVE SELECT 1
>7	Gnd			    Gnd		    +5V
>8	INDEX			    INDEX		    READY
>9	Gnd			    Gnd		    +5V
>10	DRIVE SELECT 0	    MOTOR ON DRIVE 0  MOTOR ON
>11	Gnd			    Gnd		    N/C
>12	DRIVE SELECT 1	    DRIVE SELECT 1    DIRECTION SELECT
>13	Gnd			    Gnd		    Gnd
>14	DRIVE SELECT 2	    DRIVE SELECT 0    HEAD STEP
>15	Gnd			    Gnd		    Gnd
>16	MOTOR ON		    MOTOR ON DRIVE 1  WRITE DATA
>17	Gnd			    Gnd		    Gnd
>18	DIRECTION SELECT	    DIRECTION SELECT  WRITE GATE
>19	Gnd			    Gnd		    Gnd
>20	HEAD STEP		    HEAD STEP	    TRACK 00
>21	Gnd			    Gnd		    Gnd
>22	WRITE DATA		    WRITE DATA	    WRITE PROTECT
>23	Gnd			    Gnd		    Gnd
>24	WRITE GATE		    WRITE GATE	    READ DATA
>25	Gnd			    Gnd		    Gnd
>26	TRACK 00		    TRACK 00	    SIDE 1 SELECT (HS)
>27	Gnd			    Gnd
>28	WRITE PROTECT	    WRITE PROTECT
>29	Gnd			    Gnd
>30	READ DATA		    READ DATA
>31	Gnd			    Gnd
>32	DRIVE SELECT 3	    HEAD SELECT (HS)
>33	Gnd			    Gnd
>34 	N/C			    DISK CHANGE
>
>The two FDD 26pin I have are from a TANDY 1400LT, they have the 0123
>switch onboard but the manual, from which I took the above info,
>mentions not the switches that I could find (they were set to 0 and 1
>when I yanked the drives) But the 1400 has a provision to add an
>external FDD and at the flip of a switch (on the side of the 1400) to
>make the external FDD either A or C drive.
>
>So, I guess my lingering question is: where/how do I connect the Drive
>Select lines to the 26pin FDDs?
>
>Thanks.
>
>/Chester

-- 
Cheers, Gene
People having trouble with vz bouncing email to me should add the word
'online' between the 'verizon', and the dot which bypasses vz's
stupid bounce rules.  I do use spamassassin too. :-)
Yahoo.com and AOL/TW attorneys please note, additions to the above
message by Gene Heskett are:
Copyright 2006 by Maurice Eugene Heskett, all rights reserved.